\xiti

\begin{xiaotis}

\xiaoti{已知二元一次方程 $2x - 7y = 4$，}
\begin{xiaoxiaotis}

    \xxt{用含 $x$ 的代数式表示 $y$；}

    \xxt{用含 $y$ 的代数式表示 $x$。}

\end{xiaoxiaotis}

\xiaoti{根据表中给定的 $x$（或 $y$）的值，从方程 $3x + y = 5$，求出对应的 $y$（或 $x$）的值。\\[0.5em]
    \begin{tblr}{
        hlines, vlines, stretch=1.3,
        columns={2.5em, c, $$},
        column{1} = {4em},
    }
        x & -2 & 0 & \dfrac{2}{3} & 2 &               &    &   & \\
        y &    &   &              &   & -\dfrac{1}{2} & -1 & 0 & 3 \\
    \end{tblr}\jiange
}

\xiaoti{已知二元一次方程组
    \begin{numcases}{}
        y = 1 - x   \douhao \tag{1} \\
        3x + 2y = 5 \juhao  \tag{2}
    \end{numcases}
}
\begin{xiaoxiaotis}

    \xxt{求出方程 (1) 的四个解，其中 $x = 1,\; 2,\; 3,\; 4$；}

    \xxt{求出方程 (2) 的四个解，其中 $x = 1,\; 2,\; 3,\; 4$；}

    \xxt{找出这个方程组的解；}

    \xxt{把上面的结果填入下图。}

\end{xiaoxiaotis}

\begin{figure}[htbp]
    \centering
    \input{../pic/czds2-ch5-xiti1-3}
    \caption*{（第 3 题）}
\end{figure}


\xiaoti{用代入法解下列方程组：}
\begin{xiaoxiaotis}

    \begin{tblr}{columns={18em, colsep=0pt}}
        \xxt{$\begin{cases} y = x + 3, \\ 7x + 5y = 9; \end{cases}$} & \xxt{$\begin{cases} 3x - 5z = 6, \\ x + 4z = -15; \end{cases}$}
    \end{tblr}

    \begin{tblr}{columns={18em, colsep=0pt}}
        \xxt{$\begin{cases} 3p = 5q, \\ 2p - 3q = 1; \end{cases}$} & \xxt{$\begin{cases} 9p - 13q + 12 = 0, \\ p = 2 - 3q; \end{cases}$} \\
        \xxt{$\begin{cases} \dfrac{m}{5} - \dfrac{n}{2} = 2, \\ 2m + 3n = 4; \end{cases}$} & \xxt{$\begin{cases} 3x - z = 5, \\ 5x + 2z = 25.2 \juhao \end{cases}$} \\
    \end{tblr}
\end{xiaoxiaotis}

\xiaoti{用加减法解下列方程组：}
\begin{xiaoxiaotis}

    \begin{tblr}{columns={18em, colsep=0pt}}
        \xxt{$\begin{cases} 3x + 2y = 9, \\ 3x - 5y = 2; \end{cases}$} & \xxt{$\begin{cases} 2s + 5t = \dfrac{1}{2}; \\[1em] 3s - 5t = \dfrac{1}{3}; \end{cases}$} \\
        \xxt{$\begin{cases} 6x + 5z = 25, \\ 3x + 4z = 20; \end{cases}$} & \xxt{$\begin{cases} 5s + 6t = 16, \\ 7s - 9t = 5; \end{cases}$} \\
        \xxt{$\begin{cases} 8u + 3v + 2 = 0, \\ 6u + 5v + 7 = 0; \end{cases}$} & \xxt{$\begin{cases} \dfrac{y}{2} + \dfrac{z}{3} = 13, \\[1em] \dfrac{y}{3} - \dfrac{z}{4} = 3; \end{cases}$} \\
        \xxt{$\begin{cases} 2m - 3n = 1, \\ 3m + 5n = 12.9; \end{cases}$} & \xxt{$\begin{cases} 6.28u - 4v = 0.2, \\ 8u - 5v = 1 \juhao \end{cases}$} \\
    \end{tblr}

\end{xiaoxiaotis}

\xiaoti{解下列方程组：}
\begin{xiaoxiaotis}

    \begin{tblr}{columns={18em, colsep=0pt}, column{2}={24em}}
        \xxt{$\begin{cases} 3x - y = 2, \\ 3x = 11 - 2y; \end{cases}$} & \xxt{$\begin{cases} 3(x - 1) = y + 5, \\ 5(y -1) = 3(x + 5); \end{cases}$} \\
        \xxt{$\begin{cases} 5(m - 1) = 2(n + 3), \\ 2(m + 1) = 3(n - 3); \end{cases}$} & \xxt{$\begin{cases} \dfrac{2u}{3} + \dfrac{3v}{4} = \dfrac{1}{2}, \\[1em] \dfrac{4u}{5} + \dfrac{5v}{6} = \dfrac{7}{15}; \end{cases}$} \\
        \xxt{$\begin{cases} x + 1 = 5(z + 2), \\ 3(2x - 5) - 4(3z + 4) = 5; \end{cases}$} & \xxt{$\begin{cases} \dfrac{y}{3} - \dfrac{x + 1}{6} = 3, \\[1em] 2\left(x - \dfrac{y}{2}\right) = 3\left(x + \dfrac{y}{18}\right); \end{cases}$} \\
        \xxt{$\begin{cases} v = 2.6 + 9.8t, \\ \dfrac{v}{3} - 3t = 1; \end{cases}$} & \xxt{$\begin{cases} x + y = 2800, \\ 96\% \cdot x + 64\% \cdot y = 2800 \times 92\% \juhao \end{cases}$} \\
    \end{tblr}

\end{xiaoxiaotis}

\xiaoti{解下列三元一次方程组：}
\begin{xiaoxiaotis}

    \begin{tblr}{columns={18em, colsep=0pt}}
        \xxt{$\begin{cases} 3x - y + 2z = 3, \\ 3x + y - 3z = 11, \\ x + y + z = 12; \end{cases}$} & \xxt{$\begin{cases} 5x - 3y + 4z = 13, \\ 2x + 7y - 3z = 19, \\ 3x + 2y - z = 18; \end{cases}$} \\
        \xxt{$\begin{cases} y = 2x - 7, \\ 5x + 3y + 2z = 2, \\ 3x - 4z = 4; \end{cases}$} & \xxt{$\begin{cases} 4x + 9y = 12, \\ 3y - 2z = 1, \\ 7x + 5z = 4\dfrac{3}{4} \juhao \end{cases}$} \\
    \end{tblr}

\end{xiaoxiaotis}


\end{xiaotis}